


Quantum Shenanigans

by DT Maxwell (Draya)



Series: Coffee & Carbuncles [14]
Category: Final Fantasy XIV
Genre: Carbuncle Shenanigans, Companionable Snark, Frenemies, Gen, Highlander Hyur Warrior of Light (Final Fantasy XIV), Humor, Magic and Science, Male-Female Friendship, Mathematics, Multiple Warriors of Light (Final Fantasy XIV), Nerdiness, Physics, Post-Final Fantasy XIV: Shadowbringers, Roegadyn Warrior of Light (Final Fantasy XIV), Spoilers, Synnove and Nero and Cid are weird science siblings who should not be left unsupervised ever, The Sorrow of Werlyt Questline (Final Fantasy XIV), Vitriolic Friendship, Worldbuilding, also yes Synnove's hip pouch is effectively a bag of holding with some tweaks, or a bloodbath, possibly both, you will get either an abomination of science
Language: English
Status: Completed
Published: 2020-08-10
Updated: 2020-08-10
Packaged: 2021-03-06 04:54:02
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,009
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25827763
Author URL: https://archiveofourown.org/users/Draya/pseuds/DT%20Maxwell
Summary: Or,Baby 'Buncles Break Physics (and Mom)--Nero, Cid, and Synnove yell at one another about Garlean bioengineering and the Weapons project while Dancing Heron, on Jessie's request, makes sure they don'tactuallydevolve into physical violence. Then a certain pair of baby carbuncles show up where they shouldn't, and the yelling gets louder.
Relationships: Aymeric de Borel/Warrior of Light, Cid nan Garlond & Nero tol Scaeva, Cid nan Garlond & Warrior of Light, Nero tol Scaeva & Warrior of Light
Series: Coffee & Carbuncles [14]
Series URL: https://archiveofourown.org/series/807090
Comments: 31
Kudos: 31





	Quantum Shenanigans

“This is an abomination,” Nero snarled, flipping from what little Synnove and Krile had managed to put together of the Arch Ultima on a tablet to the ones of the ravaged Ruby Weapon on a tablet. He was sitting at a heavy iron table in one of the Ironworks’s myriad workshops, fidgeting back and forth in one of the wheeled chairs Biggs had welded together on a whim one day, the chair swaying half an ilm side to side. “Absolutely repulsive. Of course, the VIIth is involved somehow, that legion has always been full of _lunatics._ ”

He was already ducking out of the way of Synnove’s hand, making to smack him upside the head for the pun, but it left him open to Cid’s hard flick against his temple. Nero yelped at the sting and pointed accusatorily at the other Garlean, yelling, “Hypocrite!”

Dancing Heron, knitting a shawl in the corner of the lab, pointedly cleared her throat.

The trio of scientists glanced over at her and then back at the tablet, subsiding into mostly-good behavior—for the time being.

Nero poked at one of the diagrams on the screen with a ferocious scowl, pinching his fingers together and then flicking them wide to expand the tiny line of code to magnification by five. He held up the tablet, nose practically against the screen as he stared at the close up of part of the recovered code from the Ruby Weapon, his eyes squinting half closed and tracking back and forth as he processed it. “Ah,” he finally said after long moments, “there it is.”

Both Synnove and Cid leaned closer—Synnove over Nero’s left shoulder, Cid over the right—and Nero pulled his head back to give them room, pointing at a small section on the screen with his pinkie finger.

“With most the Weapon melted slag and what remains of the code a scrambled nightmare, it’s hard to tell _precisely_ what swiving nonsense they’ve wrought with my schematics of the original Ultima Weapon, but that _isn’t_ anything either the Allagans had or what I added,” said the former tribune, voice grim.

Cid drummed his fingers on the worktable as he stared at the glowing code. “That looks eerily similar to what we managed to recover of Aulus mal Asina’s unique brand of horror,” he said. “Reversed, of course, since it certainly doesn’t seem like the Ruby Weapon’s oversoul system was ever intended for the pilot to _survive._ ”

“Well, in order to _implant_ the memory of an individual, one has to _extract_ it from somewhere,” drawled Synnove. “But it’s similar to the Ultima Weapon’s coding for absorbing primals, as well. So: did the VIIth manage to get their hands on mal Asina’s research; did they reverse engineer Nero’s notes; or did they come up with it independently? None of these options are particularly comforting.”

(Over in the corner, next to Heron, Tyr suddenly jerked awake from his doze, a small _*hic!*_ escaping him at the same time as his eyes crossed. Heron paused in her knitting and peered down at him, raising her eyebrows.)

“Either way, the results are _revolting,_ ” Nero said with palpable disgust. “Forcibly downloading and uploading _souls_ at a whim, who would condone such a thing?”

“ _You_ would!” Cid and Synnove snapped in unison.

“The Praetorium,” Synnove said, jabbing Nero in the kidney with her finger. He yelped and jammed his elbow into her stomach, or tried to, as Synnove was already dancing out of range as she continued: “I _distinctly_ recall you waxing poetic about adding mine and my sisters’ power to the Ultima Weapon!”

(Tyr reared up from his loaf shape to sit on his hindlegs; Heron, leaning over him, jerked back in surprise. The topaz carbuncle stared down at his stomach and carefully poked it with one paw.

Poke. Poke poke poke. Pooooooooke.

A deeply perturbed little _nya?_ escaped him as he did.)

Nero paused and set down the tablet, then pressed his forefinger against his lips as he searched his memory. “…So I did,” he said at last, grudgingly. “Not my finest moment, descending into full on megalomaniacal mad scientist stereotype.”

“That implies you ever rose from the state in the first place,” Cid muttered. And then wheezed out a curse while doubling over and clutching at his stomach; Nero had taken advantage of Cid’s momentary distraction to ram his bony elbow into the other Garlean’s abdomen.

A ball of shimmering copper wool-and-silk yarn bounced off the side of Nero’s head. Synnove cackled and plucked the ball out of the air, and, without looking, threw it back to Heron. Nero, meanwhile, grumbled wordlessly, but tucked his elbows in and folded his arms across his chest.

(As Heron dropped the yarn back into her bag of sundries, Tyr slowly lowered his front paws to the floor to properly sit, blinking slowly as he did. He looked up at Heron and let out a quiet, very bewildered _maow._ )

“I am _ruthless,_ not _cruel,_ ” Nero growled. “The Ultima Weapon absorbs entities in whole, yes, and I cannot say what happens to those entities while they are held within Ultima. But _this?_ ” He gestured to the tablet. “This is—this is using people as little more than _batteries,_ in the most disgusting, agonizing way possible, likely for no other reason that I can discern except that it was likely the _easiest_ way to—to do whatever the sodding hells it is the Legion wants to do. For all the shite I give the pair of you about your standard of ethics, I _do_ have standards, and this is still a gross perversion of science and an unconscionable lack of morality.”

Silence settled on the workshop. Synnove, Cid, and Heron all just _looked_ at Nero with various shades of bemusement.

Nero shifted uneasily, flicking his gaze from Cid, to Synnove, to Heron, and back to Cid to repeat the cycle. Finally. “…What?”

“I’m impressed, Nero,” Cid said. A smirk tugged at the corner of his mouth and he leaned back against the workbench to look at Nero with shrewd blue eyes. “You’ve actually _matured._ I never thought I’d see the day.”

“Bathe in ceruleum, Garlond.”

“Choke on a lug wrench, Scaeva.”

_HI MOMMY!_

Synnove shrieked and jumped a fulm in the air, clutching her chest. Nero shoved his chair back to get away from the flailing Highlander, so quickly he rolled over his own toes, and he made a garbled, choked off sound of wordless agony. Cid didn’t have time to get out of the way himself and ended up taking the backrest of the chair into his already abused stomach, knocking the wind from him with another wheeze. Heron did _not_ drop her needles, despite also jumping, but only because a lifetime of friendship with Rereha had trained her otherwise. Tyr jumped to all four feet with a _thud!,_ fur bristling as his gaze darted around the room for a possible threat.

All five gazes swung around to one of the other iron tables in the workshop, the one upon which Synnove had unceremoniously dropped her gear when she and Heron and Tyr had arrived.

Poking out of Synnove’s ubiquitous hip pouch, the flap still buckled shut so that their faintly iridescent heads were forced to stick out from opposite sides, ears twitching in delight and dark eyes huge with glee and utterly heedless of the minor chaos they had wrecked upon the workshop, were Amandina and Roksana.

“What in the—girls, where did you even _come from?!_ ” Synnove said, scurrying over to them. She undid the buckle and, now with room to move, the twins tumbled out of the bag with high-pitched giggles.

 _Hi Mommy hi Mommy hi Mommy hi Mommy hi Mommy,_ they chanted continuously, leaping into her arms and snuggling close, their six tails between wriggling frantically.

“Synnove,” Cid said, still breathless as he forced himself to stand upright with a wince, “I know you can be more than a little single-minded when you’re on a tear, but surely even you should have noticed two baby carbuncles that have stuffed themselves into one of your pouches.

“This is the one with the void storage metafold,” Synnove hissed, turning around. She was supporting the twins’ chests with her hands and the rest of their bodies along her forearms; Amandina was in her right hand, Roksana in the left. Amandina gently headbutted Synnove’s chin, while Roksana looked around the workshop excitedly.

Cid’s face went blank in the manner that usually preceded him asking a question he would wish he had not in fact asked at all once he had the answer: “…Void storage metafold?”

“Yes,” Synnove said primly, bouncing the twins in her arms. They giggled. “It’s based on the one Khebi built for Carby, though the structure’s internal area is only about three square fulms instead of…whatever nightmare area Carby’s is. All you have to do to make one is calculate the Cartesian coordinates in four dimensions rather than three, then fold the aether along the proper axes and—”

Cid’s eyes were becoming suspiciously glassy.

“— _Nero, kick him._ ”

Nero, using his non-injured foot, immediately did so in Cid’s shin while wearing a gleefully malicious grin. Cid shouted.

“Such an example to set,” Heron said, deadpan.

“Girls?”

The carbunclets chittered together, _When Mommy is being petty, we should use it as an example of poor behavior and not emulate it!_

“Good girls!”

Amandina and Roksana cheered.

 _(Wish Mama would take her own advice,_ Tyr grumbled. Heron made a sympathetic noise and patted him on the head.)

“What the hells was that even for?” Cid said, leaning back up against the work table to pick up his leg and rub his injured shin.

“Your eyes glazed over as I went on a brief aetherology tangent!” Synnove bellowed. (The twins made _oooooooo Uncle Cid’s in trouble~_ noises.) “I will not have it! You might be an engineering protoyping savant, but your aetherology theory is _shite!_ You have lived in Eorzea for fifteen bloody years, learn some!”

“Your grand idea for overcoming the first line of aetheric defenses of the Crystal Tower was to _throw a bloody rock at it._ ”

“It has been _four years,_ are you ever going to stop harping about that?”

“No!” Nero and Synnove snapped in unison.

“Tangent!” Heron bellowed.

Nero and Synnove grumbled but settled. Cid began the motion of a particularly rude gesture, stopped, and looked at the twins. The twins blinked at him curiously. Cid dropped his hand and crossed his arms with a scowl.

“In any event,” Synnove said, “I left the twins with Khebi and Rere to babysit—stop looking at me like that, you two, Halulu was supervising—and teleported to Revenant’s Toll directly from my office.”

Now she twisted her wrists to turn the carbunclets around to face herself, and Synnove’s expression morphed into exasperated affection as the babies beamed at her. “I waved to you!” she said to them. “You waved _back!_ How did you two get here?!”

 _We missed you, Mommy!_ said Amandina.

 _So, we decided to come find you!_ said Roksana.

 _And we tunneled!_ the black pearl carbuncle peeped excitedly, puffing out her chest in pride.

 _Yeah!_ the white pearl carbuncle said, mirroring her sister.

Synnove’s expression melted into faint confusion. The workshop was quiet for a few moments as they all stared at the twins in various degrees of bafflement.

“…Tunneled?” said Synnove, at last.

_Yeah! From Elder Cousin!_

_To your hip pouch!_

Synnove’s face blanked. Nero went white, jaw sagging open. Cid’s eyes widened to practically the size of teacup saucers.

Heron and Tyr exchanged bewildered looks.

“Before I say anything else,” said Nero, voice faint as he turned to look at Heron, “is ‘Elder Cousin’ who I think it is?”

“If you mean A’khebica’s Carby,” Heron said slowly, “then yes.”

“ _Shite,_ ” Nero hissed.

(The twins gasped and covered their mouths with their paws. _Bad word!_ )

“Carby’s a good boy,” Synnove said automatically, the tone of someone who had made the argument before and likely would again. “He’s strange, but he’s a good boy.”

Cid looked at her incredulously. “Just last week you were screaming about having to rummage in his void storage _again_ for your aether chalk and how he was gnawing on your shoulder in retaliation!”

“Carby is not a _good boy,_ Carby is halfway between a constructor-kit outer entity and an unshackled artificial intelligence.”

“He’s not _that_ bad.”

“Yes he is!” Cid and Nero snapped in unison.

“At least Carby understands ethics,” Heron muttered under her breath. Tyr snickered next to her. Then, louder, Heron said: “ _Tangent._ ”

“ _Fine,_ ” Synnove hissed. She closed her eyes and breathed in through her nose slowly; she held the breath for a few heartbeats, then let it out for the same count. When she opened her eyes, she immediately focused on the girls blinking up at her. “You tunneled. From Carby’s void storage metafold to the one in my hip pouch.”

 _Yes!_ the girls said.

 _We got a bit mixed up at first, though,_ Roksana said, ears drooping.

 _Yeah,_ said Amandina. _We almost ended up in Tyr instead._

Tyr boofed, flabbergasted, his ears pricked completely upright in shock. _That was YOU?_

Synnove _twitched._

Often as they had traveled through Azys Lla, the quartet of Warriors of Light had come across Allagan nodes glitching, five thousand years of constant functionality having degraded their circuits and systems. One type of cascading error turned the nodes’ vocalizations into a mess of garbled static, the pitch changing mid-word from high and piercing to low and growling, or vice versa. Listening to them had frequently led to the group gritting their teeth as the sounds dug into their minds and _scratched_ like broken orchestrions.

Heron, Nero, Cid, Tyr, and the twins watched the visual equivalent of that noise happen on Synnove’s face. And in the case of Nero and Cid, it was occurring on their own faces, too.

“How?” Synnove said eventually, voice tight with tension.

Amandina and Roksana looked at one another. Amandina flicked an ear, the movement briefly iridizing the black fur on the appendage into deep purple. Roksana shrugged her shoulders, her own white fur momentarily shifting blue and then back. They looked back up at their mama.

_We…pushed?_

“Pushed.”

 _Well, first we accessed Elder Cousin’s metafold!_ Amandina said.

(Nero made a strangled noise of utter horror. Cid slowly slid down the side of the worktable to sit on the floor, knees bent and staring into the middle distance.)

 _Then we had to orient ourselves,_ said Roksana. _That took a little bit. Elder Cousin’s metafold is very big!_

 _We found Auntie Rere, too,_ Amandina whispered conspiratorially. _We were playing hide and seek earlier. Elder Cousin said he had helped her._

Synnove closed her eyes and bit down on her lip, a snorting snicker briefly escaping her before she regained her self-control. Heron didn’t even bother to maintain the illusion of dignity, merely threw back her head and laughed from deep in her belly; Tyr, meanwhile, simply laid down on the floor and sighed heavily, covering his head with his paws. Nero made another horrified noise. Cid just wheezed.

_Elder Cousin helped us, too! He told us about [subspatial aetheric sympathy tension paths]._

Synnove froze. Her golden bronze skin had developed a worrying grey cast to it. “Say that again,” she breathed.

Roksana blinked. _What? [Subspatial aetheric sympathy tension paths]?_

The method by which all of Synnove’s carbuncles communicated with the people they and their mama generally liked wasn’t actual speaking, not with vocal cords and aspirated sounds to form words. Instead, they matched their aetheric harmonics with those of the individuals around them, with the end result being that the combination of the sounds they made, the body language they used, and the intent they held were “translated” into something the Spoken mind translated as “speech.” Most people initially found it odd, but quickly adapted.

This, however, wasn’t that.

Whatever Roksana had tried to tell her mama had…blanked. The concept was too big, too alien, too _what the absolute swiving fuck_ for a meat brain in three dimensions to comprehend without shutting down as a defensive tactic to preserve sanity. But the little carbunclet still spoke, and whatever it was she had said had been further translated into a strange and _obvious_ two-toned overlay of something that wasn’t quite right, but close enough.

Very slowly, Synnove turned her head to look at Nero, practically frothing at the mouth and his hands curled into claws as he grasped at air, and Cid, now aggressively cuddling a wrench he had gotten from one of his pockets like it was a comfort object. Deliberately, with precise enunciation, the arcanist said, “Please tell me I am not the only one who is hearing that harmonic as an _approximation_ and not whatever it is my child is actually saying.”

“I know what those words mean individually,” Cid said. His grip on his wrench was white-knuckled. “I may even know what those words mean _together._ I am not ready to accept that. And I am _most assuredly_ not ready to know whatever it is they are _actually_ attempting to convey.”

“Blargle,” Nero agreed.

Synnove looked back at the twins. “Continue,” she said. The corner of her left eye kept spasming.

 _Sooooooo,_ Amandina began, _once we knew_ where _to go and_ how _to sense the other metafolds based on Elder Cousin’s metafold—_

“They _sensed_ it?!” Nero yelled, outrage finally returning his ability to use vocabulary. He pushed himself upright and staggered over to Synnove and the twins, raking his hands through his hair. “How in the hells are they able to _sense_ similarly constructed aetheric metafolds when each one is a distinct pocket dimension?!” He suddenly leaned down so he was nose to nose with the twins, frowning severely and blue eyes glimmering with suspicion. In a quieter, but no less manic tone of voice: “How in the hells are you able to sense similarly constructed aetheric metafolds when each one is a distinct pocket dimension?”

 _Dunno, Uncle Nero,_ Amandina chirped, wiggling her ears, her fur iridizing back and forth between black and purple once more.

 _Just can!_ said Roksana. She reached out and very carefully booped his nose.

Nero’s eyes crossed, staring at the white pearl carbunclet’s paw. He drew back with a huff—but booped her nose in turn, and then Amandina’s. The twins peeped happily.

“And then you _pushed,_ ” Cid said from his place on the floor.

_Yeah!_

_It was easy!_

_It tickled!_

_And then we were here!_

Synnove gazed sightlessly at the far wall, green eyes huge and unblinking. She untwisted her wrists and tucked the girls up against her chest, where they snuggled close. “My babies had a conversation about aetherospatial metaphysics with _Carby,_ ” she said in disbelief. “While they were _inside_ his metafold.”

“Before they broke the laws of everything we know about physics and aetherophysics and _quantum mechanics_ and traveled through space-time because they _missed_ you,” Cid helpfully added.

“Congratulations,” Nero said icily. “You have mothered two more constructor-kit outer entities. If the fabric of reality unravels any time soon, I am blaming _you._ ”

 _Yaaaaaaaaaaay!_ the twins cheered. The air popped and a bright light flashed between them, and suddenly aetheric confetti in a rainbow of pearlescent hues floated through the air, the pieces dissipating as they landed.

Synnove dropped her gaze to her youngest carbuncles, amused exasperation briefly flitting across her features once more. Nero and Cid also looked at the carbunclets, though without the amusement on their parts. Then the three scientists looked at one another.

And, finally, the hysterical yelling commenced.

* * *

Heron let them go at it for a while, finishing up her shawl and casting on a new one with the pretty copper wool-and-silk she had earlier thrown at Nero. After nearly a full bell of non-stop shouting, Biggs and Wedge arrived to investigate, and were dragged into the hysteria once they parsed through the trio talking over one another.

She did not even _pretend_ to understand anything. There was quite a bit about aetherophysics and aetherology that she had picked up simply from knowing Synnove for so many years, but this was _far_ beyond her ken. A few phrases stood out of the verbal melee (“quantum tunneling,” “Keltgeim’s absolutely ludicrous fringe theory about particles,” “aetheric entanglement”), but otherwise it was all Allagan to her.

At the two bell mark, however, with no sign of any of them slowing down, the Hellsguard decided it was time to call in reinforcements.

“Go get Jessie, please,” Heron quietly said to Tyr, “and tell her to bring the hose.”

Tyr boofed, amused. _Yes, Aunt Heron!_ He stood and trotted for the workshop door, disappearing around it with a flick of his tails. The twins waved after him.

Heron eyed the group of frantically yelling nerds and reached up to her linkpearl cuff. She tapped a specific ‘pearl and leaned back in her chair as she waited for the other end to pick up.

A soft click echoed in her ear, and a familiar warm tenor came over the line. “Good afternoon, Heron,” said Aymeric. “What trouble has Synnove gotten into now?”

She probably _should_ start calling her baby sister’s beau for reasons other than ‘come pick her up,’ but today was not that day. “She’s involved in a five-way discussion here at the Ironworks about theoretical physics that may not in fact be as theoretical as previously thought,” she said. “Please come pick her up.”

“Quite a lively discussion, then, as _I_ can hear it,” the Lord Commander said drily. “On a scale of, _created a more efficient theorem,_ to, _about to write an “in response to” article rebutting a Thavnairian mathematician,_ just how manic is she?”

Heron hummed thoughtfully and turned to look over at the yelling scientists. Synnove was alternating with keeping Amandina and Roksana tucked close to her chest and gesticulating wildly with her hands with the twins still in her grasp, the babies going _wheeeeeeee!_ every time with the later. Nero was pulling at his hair and so wild-eyed that she was becoming mildly concerned his eyes would actually pop from his head; her Echo was softly pinging in the way that meant Nero had lost his grasp on Eorzean Common somewhere in his tirade and had slid back into Garlean. Cid had his face in his hands, only raising his head to shout something in incomprehensible technobabble before dropping it back into his palms. Biggs and Wedge weren’t even _coherent_ , with Wedge’s hands flailing so hard they were blurring.

But they all, each and every one but very especially Synnove, had a spark in their eyes that she well knew was going to mean _trouble_ for someone in the near future. Hopefully just Jessie and Thubyrgeim.

“Once she’s calmed down?” Heron said into the linkpearl. “She’ll be at, _rewriting the laws of reality._ ”

Something clattered on the other end of the line—a teacup, more than likely—and Aymeric swore softly, then sighed heavily. “Give me half a bell and I’ll be there to take her home.”

“Thank you,” said Heron cheerfully. “See you soon! Oh, and bring a towel.”

“Ah, _hells._ At least you warned me this time.” The ‘pearl line closed with a click.

And that was when Jessie entered the workshop, a firehouse braced at her hip. She waved to Heron, and the Hellsguard grabbed her knitting sundries bag and loped for the door.

The twins looked over, pricking their ears, then exchanged a glance. They nodded, and proceeded to wiggle free of Synnove, who was so deep in argument that she didn’t notice her hands emptying. Amandina landed lightly on her feet, but Roksana hit the floor with a soft _plop!_ Her sister grabbed her scruff in her teeth and helped yank Roksana upright, and then the pair were scrambling for the safety of Heron, who scooped them up outside the shop door and dropped the carbunclets into her yarn bag.

With no collateral to worry about, Jessie turned on the hose.

**Author's Note:**

> DONE JUST IN TIME FOR 5.3!
> 
> A super huge thanks to the degens of my FC, SEEK, for constant cheerleading and encouragement, with an especial thanks to [tehJai](https://archiveofourown.org/users/tehJai), [VicTheSpookyGoat](https://archiveofourown.org/users/VicTheSpookyGoat), and [chaemera](https://archiveofourown.org/users/chaemera/pseuds/chaemera) for proofing and collaborative brainstorming. I cannot claim full credit for Nero's description of Carby, that was all Chae, but he graciously let me use the line with some tweaking. \o/
> 
> A'khebica "Khebi" Ginwa and her carbuncle Carby belong to Chae, while Keltgeim belongs to Jai, and were both mentioned with permission.
> 
> And a shout out thank you to the denizens of [Emet-Selch's Wholesomely Debauched Book Club](https://discord.gg/enabling-debauched-xivfic), whose excitement for baby buncle chaos was helpful fuel when I needed an ego boost. o7


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